This is the Reedy Sonic 540 Mach 2 6.5 Turn Brushless Modified Motor. Small modifications have been made to the already competitive Sonic series to enhance performance, reliability and user-friendliness. An alloy end cap replaces the plastic version to prevent unwanted movement that could potentially make changes to the timing, but also helps to provide improved bearing alignment. Strategically placed vent holes are now slightly smaller to reduce the chances of debris getting inside the motor while still maintaining excellent airflow. Changes found internally include updated bearing sizes to help increase maximum RPM and to improve reliability, and silver-plated solder tabs reduce power-robbing resistance.

The precisio-balanced, high-strength sintered rotor has not been changed, and a variety of optional rotors are available to fine-tune for specific applications and tracks. Meets all ROAR, EFRA, and IFMAR specifications.